Anyone familiar with Heroku?

I have a small application running there using the heroku-buildpack-perl buildpack by miyagawa. It's just a small Plack application and it had been running fine for about two years.

But then, Heroku informed me that the stack it was running on was getting too old and I needed to upgrade it. "Just run a new deploy and the application will be installed to a new stack!" said they or something like that.

I inniciated a new deploy by creating an empty commit in the git repository, the deployment ran... but the application was crashing. From the logs I realised they updated the Perl version, but the deployment didn't update my XS libraries (I use local::lib, not sure if that's part of the buildpack or I set it up manually when creating the application back then).

In the end, I deleted the application and recreated it on the new stack, which worked OK. I don't keep any data anywhere so it was not a problem. What's the correct way to update the stack, though? There should be an option somewhere that tells Heroku to rebuild the dependencies, right?

Updated: Crossposted to StackOverflow.

Updated again: Answered at StackOverflow.